Ambrosia L. >

Burrs without hooked appendages, each burr containing 1 fruit (Fig. 41) Ambrosia
Fruiting head with a whorl of 4–6 spines surrounding the head near the summit, glabrous; head 2.5–4 mm diam. Leaves pinnatipartite, lanceolate to ovate, mostly up to 10 cm long; the upper ones alternate; the lower ones almost opposite. Annual herb up to 1 m high. Coast and Cumberland Plain. Weed of cultivation and waste places. Introd. from N. America. Fl. summer–autumn Ambrosia artemisiifolia